The pulmonary vasculature comprises a large conduit where certain enzymatic alterations take place, probably in large part on the endothelial cell surface. These enzymatic activities may account for local and systemic physiological alterations. Furthermore, changes in or release of the enzymes may serve as markers for vascular injury. We plan to continue our studies on enzymes of the endothelium and, in particular, on angiotensin 1 converting enzyme (A1CE), which appears to be non-covalently attached to the endothelial cellular membrane, and on lipoprotein lipase (LPLase), which may bind ionically to this membrane. In addition, other protein components of the endothelial cell membrane will be evaluated by radioactive labeling and electrophoretic procedures. A1CE will be purified from human lung and other appropriate tissues with the use of affinity chromatographic procedures we have developed for its purification from human plasma and will be characterized by enzymatic and chemical methods. It will also be localized in human tissues by immunohistochemical techniques and particular attention will be paid to tissues from patients with sarcoidosis where the enzyme is elevated in serum. The turnover of this enzyme in tissue and plasma locations will be studied both in vivo in animals and in endothelial cell cultures. Rationales for its elevation relative to albumin in bronchoalveolar lavage fluid will be evaluated. Possible lung injuries which may result in release of the enzyme bound to tissue will be studied in animal models. LPLase will be purified from calf and rat lung, its localization will be determined by immunohistochemical techniques, and binding properties to and release from tissue and cells will be evaluated. Attention will be paid to possible utilization of techniques similar to the ones above for studies of any potentially important enzyme that may be bound to the endothelial cell surface. Our long term objective is to more fully characterize components of the endothelial cell surface and to determine their relations to pulmonary disease and to systemic physiology.